Spindle assemblies of two-for-one twister textile yarn processing machines conventionally have a rotatably driven rotor mechanism including a driven whorl, a yarn reserve disc positioned above the whorl and having an outer, circumferential, yarn storage surface of predetermined diameter, a hollow axle extending axially from and above the yarn reserve disc, and a generally L-shaped yarn passageway extending axially through the hollow axle and partially through the yarn reserve disc and then radially through the yarn reserve disc and having an exit aperture in the storage surface. During processing of yarn in such spindle assembly of a two-for-one twister textile yarn processing machine, yarn is withdrawn from a supply package and is passed through the yarn passageway of the rotor mechanism and exits therefrom at the yarn storage surface where several wraps or coils of yarn may be taken-up on the yarn storage surface prior to further passage of the yarn through the spindle assembly of the machine for processing in a well-known manner.
In the event of yarn breakage during operation of the yarn processing machine, rotation of the rotor mechanism is stopped for piecing-up of the yarn. Unfortunately, yarn continues to be withdrawn from the supply package and wrapped or coiled around the yarn storage surface of the yarn reserve disc until the rotor mechanism has been completely stopped, due particularly to centrifugal force which acts on the yarn emerging radially from the yarn passageway through the yarn reserve disc.
Conventionally, these yarn reserve discs have a short annular rim extending radially outwardly from a lower portion of the yarn storage surface which is the result of the machining process utilized in constructing the yarn reserve disc, i.e. machining of a cylindrical workpiece to have an uninterrupted outer circumferential yarn storage surface of predetermined diameter. This resulting annular rim is an incidental resulting feature rather than a component provided for any specific purpose.
As a result of the phenomenon described above with respect to yarn breakage and further wrapping or coiling of yarn around the yarn reserve disc during stopping of the rotor mechanism, a problem often occurs of the coils of yarn slipping down off of the yarn storage surface of the yarn reserve disc into an area occupied by the driven whorl. If this results, subsequent driving of the rotor mechanism of the spindle assembly through the whorl is hampered.
It has been determined that the annular rim at the lower portion of the yarn storage surface of the yarn reserve disc, incidentally provided as a result of machining, will not sufficiently prevent the yarn coils from slipping off of the yarn storage surface and, therefore, does not overcome this problem.
Specific attempts to overcome this problem have been primarily directed to providing thread clamping devices which, in the event of yarn breakage, are intended to swing across the path of the yarn between the supply package and entry of the yarn into the yarn passageway through the spindle assembly to trap the yarn at this point. For reasons of expense, such mechanisms are predominantly of a mechanical nature. The prevailing conditions, such as dust, lint and lack of care in operation are often very unfavorable and the reliability of these clamping mechanisms suffer for these reasons and quite frequently are inoperable. When this results, the problem described above still exists.